This invention relates to a novel self-load-balancing chin-strap harness structure (or chin-strap system) for use in a protective, safety helmet—a kind of nominally unconstrained, “self-seeking” structure which addresses a number of significant disadvantages found in conventional harness structures of this general character. As will be seen, the concept “nominally unconstrained” refers to the fact that the structure and implementation of this invention include almost nothing in the way of rigidly configured, non-moveably anchored (at least with respect to certain appropriate degrees of freedom of motion) characteristics, insofar as permitting this structure to self-seek a true load-balanced proper condition when employed with a safety helmet. Flexible and pliable fabric-like components, along with a pair of lateral sliding connections, lead to this important performance quality of the invention.
In connection with the disclosure of this invention herein, two special descriptive words/expressions are employed with respect to certain structural characterizations of the invention. These expressions are “symmetriflex” and “symmetriload”.
The term “symmetriflex” refers to a quality of the harness structure of the invention involving bilateral symmetry of component flexibility which is offered by the fabric, strap-like, pliable and flexible materials employed substantially entirely/throughout the various elements of the invention. This quality is generally lacking in conventional prior art chin-strap harness structures, wherein, for example, laterally offset, laterally “unbalanced” rigid-body, strap-connection hardware, typically associated with a chin-strap unit per se, is employed.
The term “symmetriload” refers to another quality of the invention which is that, when it is user-cinched and in use, stabilizing and anchoring a helmet in place on a wearer's head, load distribution, in the form of strap tension, is substantially bilaterally load-balanced, with no harness strap component being either noticeably slack, or noticeably over-tensed, in relation to its “mirror-image”, bilateral matching companion component. This quality is also generally lacking in prior art structures, especially where rigid-body, strap-connection hardware of the type generally mentioned just above is employed, and/or where the point of connection between the effective lateral end of a chin-strap unit per se is anchored in a fixed-position manner to the usual pair of lateral strap, or strap-like, structures which typically anchor directly to the shell of a helmet.
The concepts of bilateral load balancing, and of load-balanced centering, as employed herein, are intended to relate to a situation wherein, with the invention in use in relation to an associated user-worn helmet, all of the flex-strap components of the invention have self adjusted (during user cinching) to conditions in which different “length parts” of these components effectively meet and connect with one another at two, three-way points of intersection disposed on opposite sides of the helmet, and: (a) each length part extending away from each such point of intersection is substantially purely in tension; and (b) at each point of intersection, there is no tendency of a force carried in any one of such length parts to urge a shifting of the intersection point relative to either of the other two length parts which extend away from that same intersection point. These concepts also include the idea that like portions of the flex-strap components of the invention, disposed on opposite sides of an associated helmet which is in use, carry substantially equal tension loads.
A typical chin-strap harness, including even quite recent entrants into this field of technology, features a pair of strap-like side-strap components, each usually formed with a pair of elongate, defined-length, fixed-angularly-intersecting, lateral strap sub-components which, at their region of fixed angular intersection, intentionally furnish fixed anchoring locations for securement of the outer ends of the usual pair of releasably length-interconnectable, elongate chin-strap elements which together make up a chin-strap unit, or substructure. The term “length-interconnectable” is used herein to describe an arrangement wherein a chin-strap unit achieves its full length through the use of a rigid-body, releasable connection device which, in a lengthwise context, fastens two adjacent ends of two elongate elements which are brought together to create a fully assembled, full-length chin-strap unit.
An illustration of such a recently introduced harness structure is found in the helmet system which is disclosed in U.S. Pat. No. 6,804,829 B2, issued Oct. 19, 2004 to Crye et al. The spaced ends of the side-strap sub-components employed in this system, which sub-components are rigid and springy rather than flex-strap and fabric-like, are anchored, in a very traditional manner, to pairs of essentially fixed-position points appropriately provided on the inside of a specialized helmet shell component. The length-interconnectable chin-strap elements employed also in this system, when interconnected to form, collectively, an overall chin-strap substructure, cooperate to provide chin-engaging componentry which is supposed to center accurately on the wearer's chin.
The disadvantages of this kind of conventional arrangement, in its various forms (with rigid or flexible side-strap sub-components), are numerous. To begin with, proper positional placement of that portion of the chin-strap which is intended to center upon and engage the chin is notably difficult to achieve, particularly in the situations where flexible fabric-like side straps are involved. Adjustments to accomplish “load-balanced” centering are often quite challenging. Fixedness of the locations where the outer ends of chin-strap elements connect to the two, lateral side-strap sub-components contributes both to this centering problem, and to the fact that the two pre-fixed-length elongate portions of such sub-components rarely share equally in tension load-bearing when a chin-strap is tightened against a wearer's chin. In point of fact, one or the other of these fixed-length portions in each side strap is often quite slack. Such a condition leads either (a) to helmet instability on the head, (b) to strange angular “cocking” of a helmet on the head in a manner which, because of conventional design, as distinguished from that of the present invention, laterally imbalances load-sharing in a helmet harness structure, and thus undesirably imbalances load-cushioning for the head, or (c) to both. Adjustment to correct this kind of condition, and to keep all parts of a helmet, including the importantly cooperating chin-strap substructure and shell-internal, load-cushioning structure (usually shock-absorbing pads), properly shock-absorbingly positioned relative to one another, and especially so when the associated helmet may be cocked at an “odd angle” on the head, often is just not possible because of the precommitted fixed (defined) lengths of the side-strap sub-components
The releasable length-interconnection mechanism which is most often supplied for coupling the usual two chin-strap elements is (a) typically quite bulky, (b) normally offset to one side of the chin and jaw when the chin-strap elements are coupled for use (see for example what is illustrated in the mentioned '829 patent), and (c) notably easily breakable. Its presence, in addition to being often quite uncomfortable, in that it bears as a “protrusion/enlargement” against one side of the face, results (a) in significant non-bilateral symmetry in overall harness disposition and performance, and, relatedly (b), in appreciable non-uniformity with respect to flexibilities and performance responses of the two lateral sides of a chin-strap harness because of the introduced, nonflexible rigidity which exists in the interconnect mechanism per se.
Another important drawback regarding prior art helmet harness structures is that they may enhance springiness in the manner in which an associated helmet system engages a wearer's head. Contrary to the long-standing, conventional-approach belief that springiness is an asset in handling shock cushioning, it is actually a serious and dangerous detriment. It amplifies rather than moderates a shock event. A good illustration of this problem of enhancement is found in the above-referred-to '829 patent which includes a pair of rigid and springy fixed (nominally) angular side members to which a chin-strap unit is attached.
Another issue presented by the '829 patent structure is that the specific force carried in each “leg” of each of the rigid, springy side members can tend to try to shift the point of three-way intersection existing between the other leg in that side member and the associated, connected of the chin-strap unit. Thus, this situation disables the '829 structure from predictably achieving and implementing the concept of load balancing described above in relation to the present invention.
The chin-strap harness of the present invention definitively addresses all of these conventional-structure disadvantages.
As will become clear from the detailed description of the invention which follows below, and especially when this description is read in conjunction with the accompanying drawings, the structure of the present invention features (a) simple and complete bilateral symmetry in all load-balancing respects, including the unique structural-symmetry symmetriflex and symmetriload qualities mentioned earlier herein, (b) sliding rather than fixed connections between flexible and pliable side straps and the opposite ends of a chin-strap substructure, (c) non-fixedness in the relative lengths, and in the angularities of intersections between “legs”, of the harness side straps (they are fabric-flexible), (d) automatic self-load-balancing “centering” for the chin-strap substructure which is unitary in nature, and (e), as just suggested earlier, substantially symmetriload, and symmetriflex load-handling by the elongate portions (the “legs”) in the side-strap “lengths” which extend away from the points of sliding connections established with the outer, laterally-load-balanced ends of the chin-strap substructure.
Other features and advantages, such as structural simplicity, the absence of anything which might introduce, or contribute to springiness into the cooperative behavior of the invention with a helmet shell, and ease of use with a wide variety of helmets, will also become clearly apparent as the description of this invention now unfolds.